package com.rybbaby.tss.tasks.core.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
* @ClassName: MD5Util 
* @Description: 
* @author  Liucx
* @date 2014-5-9 下午6:08:43 
* 
* @tag  v1.0
 */
public class MD5Util {

	private static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
	
	private static MessageDigest messagedigest = null;
	
	static {
		try {
			messagedigest = MessageDigest.getInstance("MD5");
		} catch (NoSuchAlgorithmException nsaex) {
			System.err.println(MD5Util.class.getName() + "初始化失败，MessageDigest不支持MD5Util。");
			nsaex.printStackTrace();
		}
	}

	public static String getFileMD5String(File file) throws IOException {
		FileInputStream in = new FileInputStream(file);
		FileChannel ch = in.getChannel();
		MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0, file.length());
		messagedigest.update(byteBuffer);
		in.close();
		return bufferToHex(messagedigest.digest());
	}

	public static String getMD5String(String s) {
		return getMD5String(s.getBytes());
	}

	public static String getMD5String(byte[] bytes) {
		messagedigest.update(bytes);
		return bufferToHex(messagedigest.digest());
	}

	private static String bufferToHex(byte bytes[]) {
		return bufferToHex(bytes, 0, bytes.length);
	}

	private static String bufferToHex(byte bytes[], int m, int n) {
		StringBuilder StringBuilder = new StringBuilder(2 * n);
		int k = m + n;
		for (int l = m; l < k; l++) {
			appendHexPair(bytes[l], StringBuilder);
		}
		return StringBuilder.toString();
	}

	private static void appendHexPair(byte bt, StringBuilder StringBuilder) {
		char c0 = hexDigits[(bt & 0xf0) >> 4];
		char c1 = hexDigits[bt & 0xf];
		StringBuilder.append(c0);
		StringBuilder.append(c1);
	}

	public static boolean checkPassword(String password, String md5PwdStr) {
		String s = getMD5String(password);
		return s.equals(md5PwdStr);
	}

	public static void main(String[] args) throws IOException {
		long begin = System.currentTimeMillis();
		File big = new File("d:/test/20130220140699.csv");
//		20130220140636.csv
		String md5 = getFileMD5String(big);
		long end = System.currentTimeMillis();
		System.out.println("md5:" + md5 + "time:" + (end - begin) + "ms");
	}
}